Our work during the coming year will be concerned with investigation of lambda met transducing phage and the in vitro expression of met genes carried in the chromosomes of these viruses. We have partially completed low resolution mapping of several of our transducing phage using restriction enzymes and electron microscopy of heteroduplexes. In addition to measuring the exact bacterial DNA content of these phage we have roughly positioned three met genes. We plan to do higher resolution mapping by a combination of procedures including restriction nuclease digestion, transposon insertion, deltion isolation, recombinant DNA methodology and electron microscopy. With the results of these studies we hope to precisely locate the four met genes near 87 min. on the E. coli chromosome. This information should allow us to construct a number of vectors for specific purposes such as MRNA hybridization, identification of the protein products of particular genes such as met J and the construction of strains which overproduce these products. We plan to isolate the products of several met genes including metB metF and metJ. We will also continue to study factors that influence the in vitro expression of met genes and if we are able to purify or partly purify the metJ gene product we will evaluate its effect on in vitro enzyme synthesis. As appropriate vectors become available we will measure in vivo and in vitro control of transcription.